This invention relates to: a three-dimensional woven fabric which is comprised of warp yarns, weft yarns, and a second-warp yarns for cross-linking opposing web plies, and which is useful as a structural reinforcement material; together with the method for weaving that fabric and the apparatus specifically needed to accomplish that weaving method.
Various patent applications have been made in the past relating to three-dimensional woven fabrics for industrial use and the methods for weaving them. Representative of these three-dimensional woven fabrics for industrial use are three-dimensional woven fabrics woven so that the warp yarns, the weft yarns, and the vertical-direction yarns, which are arranged at right angles to each other, are all cross-ridged with respect to one of those sets of yarn. In addition, as a method for weaving that type of three-dimensional woven fabric, a method (Japanese Patent Publication (S)61-1538) has been proposed in which the carrier arm of the bobbin carrier which revolves around one of the said warp, weft, and vertical-direction yarns holds the bobbins which contain the other two component yarns, and an operation is repeated in which, by the revolution of said carrier arm, those bobbins are successively transferred to the carrier arms of the adjacent bobbin carriers, and said bobbins containing those other two component yarns are moved in different perpendicular directions.
However, with the three-dimensional woven fabric described above, the construction of said three-dimensionally woven fabric was not such that it was possible to freely increase the coarseness of the structural gaps (freely form spaces or gaps within the structure) of the fabric. Therefore, when using the woven fabric having this type of construction as a foundation for industrial use, for example, as a reinforcement foundation (reinforcement material) for the cement of a concrete structure, or as a reinforcement foundation for the composite members of an aircraft, space station, etc., it was not possible to supply the amount of cement, resin, etc., into the woven structure needed to achieve the intended function, thus posing problems for use as a reinforcement material.
In addition, although the three-dimensional woven fabrics such as that described above are woven using methods such as that disclosed in the aforementioned Publication (S)61-1538, with the prior art methods such as this, because the bobbins containing the two component yarns described above would interfere with each other if they were simultaneously moved in perpendicularly intersecting directions, it is not possible to move the bobbins simultaneously. Thus, when weaving a three-dimensional woven fabric using this type of method, because each of the bobbins must be moved successively at different times in the corresponding intersecting directions, one weaving cycle (for example, one cycle in which the weft yarns and the warp yarns are woven just once with respect to the vertical-direction yarns) requires as much time as a few minutes, thus presenting the drawback of making commercial mass production difficult.
Furthermore, with the weaving method described above, because of the nature of the method, it was not possible to beat up the weft yarns tightly against the warp yarns using a reed, and as a result, only fabrics in which the density of the web constructed of the warp yarns and the weft yarns was relatively low could be woven, and the weaving method was not adequate in cases where a high density web was required.
In consideration of the conditions described above, the objective of this invention is to propose: a three-dimensional woven fabric for which it possible to freely form spaces of any desired size within the woven structure of the three-dimensional woven fabric, which can be efficiently woven, and which also has a construction in which it is possible to increase the density as needed; together with the method for weaving said three-dimensional woven fabric and the apparatus specifically needed to accomplish that weaving method.